1. Field of the Invention
The present invention relates to a stent delivery system and a stent delivery method for indwelling a stent at a hollow site of a digestive system, respiratory system, urinary system, reproductive system or the like by using an endoscope.
2. Background Art
Stents are used for obtaining a path that restores the function of an organ having a structure or a blockade having occurred somewhere in the hollow organs such as the digestive system, the respiratory system, the urinary system or the reproductive system.
In many cases in recent years, a maneuver of disposing a stent to a site of the aforementioned hollow organ which must be treated uses an endoscope and a specific treatment instrument. For example, U.S. Pat. No. 5,921,952 discloses a stent delivery system which is used for such maneuver. Specifically, it is provided with a guide catheter, a guidewire, a pusher tube and a suture (a filament) for connecting a stent to a distal end of the pusher tube in a manner that the stent can be removed. The guide catheter inserted in an inner hollow portion of the stent and is inserted in a living body together with the stent. The guidewire is inserted in the inner hollow portion of the guide catheter and guides the guide catheter and the stent in the living body. The pusher tube, of which the guide catheter is inserted in the inner hollow portion, is inserted in the living body together with the guide catheter and presses the stent along the guide catheter. The suture is passed through a hole which is formed in the distal end of the pusher tube, and both ends of the suture are tied so as to make a ring. In addition, a part of the suture is passed through the inner hollow portion of the stent through the hole which is formed in the stent and is forming a loop. The distal end of the guide catheter inserted in this loop prevents the suture from being detached from the stent. That is, the stent is connected to the distal end of the pusher tube via the suture detachably.
First in the procedure, four members combined like the above, i.e. the stent, the guide catheter, the pusher tube and the suture, are inserted into a channel which is formed along the guidewire in the inserting portion of the endoscope, and are protruded from the distal end of the inserting portion, and then the distal end of the stent and the guide catheter is inserted in the portion of the hollow organ where the treatment is necessary.
Subsequently, the guide catheter is pulled from a channel in the retracting direction while the guidewire and the pusher tube are maintained at a prescribed position. The guide catheter in this state may not have to be fully retracted. Drawing the guide catheter causes its distal end to be retracted from the loop of the suture, thereby releasing the stent from the guide catheter. Subsequently, the guidewire is pulled from the channel of the inserting portion of the endoscope in the retracting direction similarly to the guide catheter. The guidewire in this state may not have to be fully retracted. Drawing the guidewire causes its distal end to be retracted from the loop of the suture, thereby releasing the stent from the guide catheter, and releasing the engagement between the stent and the pusher tube via the suture.
Further pulling the pusher tube from the channel in the retracting direction causes the stent alone, which has previously been released from the pusher tube, to be indwelled at a site of the hollow organ which must be treated.
In the above-described procedure, when the distal end of the stent and the guide catheter is inserted in the portion of the hollow organ where the procedure is necessary, if the stent is arranged back from the portion where the procedure is necessary, the pusher tube is pulled a little before the guide catheter and the guidewire is pulled, that is, before the engaging relation between the stent and the pusher tube is released. This allows the stent connected to the distal end of the pusher tube to be returned to a desirable position.